FVL mutation is a major inheritable risk factor for thrombophilia in the Western population accounting for 20% to 25% of patients with VTE.[7,8] However, the incidence of FVL has not been previously reported in Korea, Japan, or China until now.[9,10] For it had never been reported in Korea before, the Korean Society of Thrombosis and Hemostasis does not recommend routine screening of FVL for patients suspected of inherited thrombophilia. The gene discussed is F5; the disease is Rare hereditary thrombophilia.